Do You Need to Train to Failure to Grow Muscle?

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Success isn’t always about greatness. It’s about consistency. Consistent hard work gains success. Greatness will come.
––Dwayne “The Rock” Johnson

Note: Updated in August 2022.

In the lifting community, some people believe you must go to failure on every single set because, “no pain, no gain, bro!”
 
Other people claim you must avoid failure because, “injury and fatigue, bro!”
 
But which one is the best approach to optimal muscle growth? Is there a single best approach?
 
This article will tackle these questions and cover the following points:
 

• What is muscular failure?
• Is it necessary to grow muscle?
• When would you want to train to failure?

What is muscular failure?
 
A journal article from 2016 defined muscular failure as “the inability to move a specific load beyond a critical joint angle or (…) incapacity to complete a repetition in a full range of motion due to fatigue.”
 
For example, when you reach muscular failure on the bench press, you can’t push the bar off your chest, so you squirm in a rather undignified manner and wave your hand at the person next to you to get help. I might or might not be speaking from experience.
 
You may have also heard the term technical failure, which occurs when you can’t perform another repetition with correct technique.
 
For instance, on an ass-to-grass squat, you would reach technical failure when you start doing quarter squats.
 
Throughout this article, I will be referring primarily to muscular failure.
 
Is muscular failure necessary to grow muscle?
 
Before we can get to the answer, we need to start from the following question: How does muscle growth happen?
 
First off, muscle growth is a complex process, which we don’t fully understand yet.
 
In humans, muscle growth seems to occur primarily through a physiological process called hypertrophy, which is an increase in the size of the muscle cells (also referred to as muscle fibres).
 
It can also take place through hyperplasia, which is an increase in the number of muscle fibres. This appears to be more common in animals than humans. 
 
There’s a lot we don’t yet know about hypertrophy, but there seems to be a reasonable amount of evidence to suggest that mechanical tension is one of the main drivers of this process.

A muscle fibre senses mechanical tension when that fibre produces force against an external or internal resistance. Respectively, a dumbbell and your bodyweight are examples of external and internal resistances.
 
Does that mean you don’t need to reach failure, because, as soon as you start curling that EZ bar, the muscle fibres in your biceps will get all the sweet mechanical tension they need? Not exactly.
 
The thing is, we don’t immediately start using 100% of the fibres in our muscles the moment we begin a set.

In addition, the more muscle fibres contribute to a set, the higher the number of fibres that receive a hypertrophic stimulus, the greater the overall growth of that muscle.

So how do we recruit our muscle fibres?
 
Each fibre is connected to a neuron, and each neuron in turn is linked to a number of fibres. Neurons give the fibres the order to activate and contribute to a movement. A neuron and all of the fibres it “supervises” – or innervates, in technical terms – is called a motor unit.
 
These motor units are then fired according to Henneman’s size principle, from smallest to biggest.
 
The bigger motor units are primarily made up of fibres known as fast-twitch fibres, which can produce a lot of force, but also fatigue fast. These are the fibres that appear to grow the most with hypertrophy training.
 
At the beginning of a set, the first motor units to be recruited are smaller units comprised primarily of slow-twitch fibres, which produce less force than fast-twitch fibres, but can keep going for longer.

The closer we get to muscular failure, the more force we need to produce in order to complete the same movement. That’s when we start recruiting more and more, and bigger and bigger motor units, including those that contain fast-twitch fibres.
 
By training close to or to failure, we can therefore accomplish two goals:

• Recruit as many muscle fibres as possible, including the higher-threshold motor units
• Get each recruited fibre to produce high levels of force and thus perceive high levels of mechanical tension

This makes training close to failure extremely effective for hypertrophy.
 
Is failure training superior for hypertrophy to training in close proximity, but not quite to failure?
 
The answer to this is not so clear-cut.
 
Indeed, going to failure is a fool-proof way to recruit all of the fibres within a muscle. However, this also produces the highest amount of fatigue, which might compromise your training performance within the same session and over a longer period of time.
 
Furthermore, it’s possible to recruit higher-threshold motor units even without hitting failure on every single set. Specifically, it looks like staying within three reps from failure may be more than enough to make gains that are similar in magnitude to those you’d make if you went to failure on every set.
 
Therefore, you could go to failure on every set to ensure you’re always recruiting all of your fibres. However, the evidence on whether this approach is superior to training just shy of failure is limited and mixed at the moment.
 
On the other hand, we can be pretty sure that training close to failure will help us make good gains, and it can allow us to manage fatigue a little bit better than failure training. The only downside is that it can be easy to think you’re training “hard enough”, when in fact you’re way too far from failure to see any changes in your muscular development.
 
A tool I’ve found most helpful to reach the appropriate proximity to failure whilst improving fatigue regulation in my own and my clients’ training is the RPE or RIR scale.
 
When could you benefit from training to failure?
 
Now you know that you may not need to train to failure to optimise muscle growth, but you still need to train hard enough to make it happen.
 
Nevertheless, I’m not suggesting you avoid failure training altogether.

In fact, I think it can prove useful in a variety of scenarios, such as the following:

• Instead of aiming for the same RPE target every week, you could start from three or four reps away from failure and increase intensity of effort every week until you hit failure in the final week of your training block, then you deload and repeat. This is what I’ve been doing in my own training for about three years as of August 2022.
• If you haven’t taken a set to failure in a long time, you can go to failure on the last set of each exercise in your session to check whether you’re still training hard enough (using a “last set, best set” approach).
• If you’ve never experienced failure, then it’s unlikely you can use the RPE or RIR scale because you simply don’t know what “failure” means. Therefore, going to failure on various exercises where it’s relatively safe to do so, can teach you what true failure feels like for every muscle in your body.
• If you know you tend to “chicken out” of a challenging set unless you train to failure, then maybe this is the best training approach to ensure you get the most hypertrophic bang for your buck.
• Some people find that overcomplicating their training puts them off of it. If that’s the case, and you think that RPE and RIR are excessively complicated methods to gauge progress, failure training might be the key to your consistency. And, in the end, you can’t make gains if you don’t train, so consistency should be your top priority.

 
Practical Takeaways
 
There’s a time and place for failure training, just like there’s a time and place for leaving reps in reserve.
 
The key to optimal gains is the understanding that neither is a magic ticket to the Valley of Muscle.
 
Among approaches that science hasn’t yet deemed completely counterproductive, the best one is ultimately the one enjoy the most and can apply it with the utmost consistence.

Thanks for reading. May you make the best gains.
 
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